ABSTRACT

The indiscriminate usage of antibiotics in human and animal therapy has been reported severally in the last decades. This act has subsequently caused the emergence and spread of antibiotic resistance thereby resulting into severe environmental and public health problems. This study was therefore aimed at detecting and characterizing antibiotic resistant enterobacteria from wastewater in hospital and non-hospital environments in Benin-City.

A total of sixty (60) untreated wastewater samples were collected from different sites in hospital environments and non-hospital environments over a period of six months from January 2019 to June, 2019. The samples were screened for enterobacteria using culture-based techniques and Analytical Profile Index 20E (API 20E). The antibiotic susceptibility profile of the isolates was carried out using the Kirby-Bauer disc diffusion method while extracellular virulence factors and biofilm formation were examined using the standard bacteriological and microtitre plate method.

The highest heterotrophic bacterial count from hospital environment was observed in site 2 (296 ± 7.49 x109 CFU/mL) while the lowest was seen in site 4 (18 ± 0.28 x109 CFU/mL). The highest heterotrophic bacterial count from non-hospital environment was observed in site 1 (297 ± 7.50 x109 CFU/mL) while the lowest was observed in site 5 (12 ± 0.80 x109 CFU/mL) respectively. The highest occurrence of Enterobacteria isolates obtained from different sources of wastewater were; Klebsiella pneumoniae [hospital sources 4/25(16.0%), non-hospital sources 5/25(20.0%)] and Escherichia coli [hospital sources 5/25(20.0%), non-hospital sources 4/25(16.0%)]. The susceptibility profile revealed that the highest susceptibility was observed in Klebsiella spp. (100%), E. coli (100%), Shigella spp. (100%) and Salmonella spp. (100%) against gentamicin, while the lowest was observed in Citrobacter spp. with 0% susceptibility against both ampicillin and fosfomycin. The multiple antibiotic resistance (MAR) index of the enterobacteria isolates from hospital and non-hospital sources of wastewater showed that highest multiple antibiotic resistances was observed in Pseudomonas spp. with MAR index ranging from 0.5 to 0.9 while the least was seen in Shigella spp., E. coli and Klebsiella spp. with MAR index ranging from 0.2 to 0.4 respectively. A total of 48/50(96%) of the enterobacteria isolates produced biofilm while 2/50(4%) were negative. The results also showed that extracellular enzyme formed by enterobacteria isolates were β-haemolytic [hospital sources (84%), non-hospital sources (52%)], gelatinase [hospital sources (64%), non-hospital sources (56%)], protease [hospital sources (68%), non-hospital sources (60%)] and DNA degrading activity [hospital sources (36%), non-hospital sources (64%)]. This study therefore emphasize, that the use of adequate procedures such as proper use of antimicrobial drugs in hospitals, veterinary care and aquaculture, will contribute to more efficient control of the dissemination of resistant bacteria in the environment.